a) Field of the Invention
Microscope systems in which the photoemission of occurring defects ("hot spots") is subjected to spectral analysis are known for failure analysis of semiconductor circuits. By "hot spots" is meant weak light emissions which occur at defects in electronic circuits when connected to a power supply. Spectral detection of these defects represents a fingerprint for the location in question; that is, conclusions can be reached concerning the source of the defect in the manufacturing process from the spectral configuration.
a) Description of the Related Art
Currently, such hot spots are detected, for example, by devices which are outfitted with exchangeable metal interference filters. ("Photoemission Spectrum Analysis--A Powerful Tool for Increased Root Cause Success", J. S. Seo; S. S. Lee; C. S. Choe; S. Daniel; K. D. Hong; C. K. Yoon; ISTFA 95, 21st International Symposium for Testing and Failure Analysis, Nov. 6-10 1995, Santa Clara, Calif.).
They have the disadvantage that the individual wavelengths of the spectrum to be analyzed are received serially by swiveling in appropriate filters which requires a plurality of filters and time expenditure if a sufficiently closely graded spectrum is needed. In addition, the calibration is problematic.
It was further suggested to pick up the photoemission with an elliptical mirror and to image it on a fiber input ("A High-Sensitivity Photo Emission Microscope System . . . ", Tao; Chim; Chan; Phang; Liu, Centre for Integrated Circuit Failure Analysis, Singapore). This light is fed to a scanning monochromator with SEV via the fiber and is spectrally detected. An X-Y positioning stage brings the focal point of the mirror to the location of photoemission.
Further, arrangements of a microscope in combination with a camera are known for evaluating photoemissions ("Photoemission Spectrum Analysis . . . ", ISTFA, November 6-10, Santa Clara, Calif.). The evaluation is effected in a wavelength-dependent manner with narrow-band exchangeable filters.
Spectral analysis of microscopically small light-emitting objects also has great importance in general for technical and biological analyses. If only partial areas are to be subjected to spectral analysis in the microscopic examination, the insignificant area is generally excluded by a defined selection of pinholes or diaphragms in the beam path and the remainder of the microscopic image is imaged on the entrance slit of a spectrometer following in the beam path, which can be formed, for example, by a dispersive element and a surface receiver. This device construction requires considerable space (auxiliary add-on to the microscope) and is problematic especially as concerns light-absorbing or light-arresting objects due to the limited light-conducting capacity of the spectrometer. Further, this solution brings about considerable costs. Combinations of microscopes and spectrometry arrangements are known, for example, from DE 4419940 A1.